Design and characterisation of auxetic lattice with controlled transitions to near-zero Poisson’s ratio

Auxetic materials, defined by their negative Poisson’s ratio, exhibit enhanced toughness, energy absorption, and improved shape retention, making them attractive for aerospace, biomedical, and flexible electronics applications. In contrast, materials with near-zero Poisson’s ratio maintain lateral dimensional stability during deformation, which is essential for precision-dependent structures. This study investigates the geometric tuning of Poisson’s ratio in porous auxetic lattices through design optimisation. Four configurations, including re-entrant H-based, re- entrant V-shaped, elliptical hole-based, and peanut-shaped hole geometries, were examined by varying key parameters, including the rib inclination angle in re-entrant structures and the rotation angle of elliptical units. ABS samples of consistent dimensions were analysed using finite element simulation. The results reveal a clear relationship between geometric configuration and Poisson’s ratio transition behaviour, confirming that small adjustments in inclination or rotation angle can shift the response across negative, near-zero, and positive regimes. Among the structures examined, the elliptical hole-based lattice demonstrated the most stable transition, achieving a near-zero Poisson’s ratio at approximately 25.45°, while peanut-shaped geometries showed more abrupt transitions, and re-entrant forms predominantly retained auxetic behaviour. These findings establish inclination angle as a controllable design parameter for tailoring lateral deformation characteristics, supporting the design of multifunctional materials where either auxetic expansion or dimensional stability is required.